Each day, worldwide, hundreds of thousands of patients visit blood collection centers for the purpose of getting their blood sampled for eventual or immediate diagnostic testing. During a patient visit, the phlebotomist punctures the patient's superficial vein (usually an arm vein) with a hollow needle and blood is aspirated into evacuated plastic or glass tubes. These plastic or glass tubes usually contain anticoagulants or procoagulants, compounds that are placed as liquid into the blood collection tube or sprayed onto the inside surface of the tube. For these anticoagulants (or procoagulants) to work properly, the fresh incoming blood must be adequately mixed with the anti- or pro-coagulant. In the absence of mixing or because of insufficient mixing, the incompletely reacted blood can form clots that can result in the malfunction of the blood analyzer (including plugging) or an incorrect analysis of the blood specimen leading to diagnostic errors and delays in diagnosis. One example of insufficient mixing causing misdiagnosis is falsely elevated troponin (an indicator of myocardial infarction) in plastic blood tubes containing the anticoagulant lithium heparin. Moreover, despite continuingly reminding blood drawing staff to mix their blood tubes after drawing, the inversion step constitutes only one of a great many steps in the typical phlebotomy process, and there are considerable external and internal pressures that hurry the phlebotomist.